Method of setting an expansion anchor

ABSTRACT

The trailing end of a forwardly diverging first member is releasably engaged by the front of a second member, the rear of which is configurated for engagement by a drill chuck. Both members are jointly rotated about their common longitudinal axis to drill a hole into a wall with cutting edges provided on the leading end of the first member. The second member is then disengaged from the first member and withdrawn. An expansion member having a slot in its front end is inserted into the hole and so oriented that the trailing end of the first member enters the slot, whereupon the expanding member is further driven into the hole so that the divergence of the first member radially expands the front end of the expansion member as the trailing end enters deeper into the slot.

United States Patent [19] Fischer [451 Apr. 9, 1974 METHOD OF SETTING ANEXPANSION 21 Appl. No: 301,674

Related US, Application Data [62] Division of Ser. No. 23,339, March 27,1970, Pat.

[30] Foreign Application Priority Data Sept. 19, 1969 Germany 1947369[52] U.S. Cl. 29/432, 29/522 [51] Int. Cl B23p 11/00 [58] Field ofSearch 29/432, 432.2, 522; 85/68; 175/394 [56] References Cited UNITEDSTATES PATENTS 1,449,624 3/1923 Phillips 85/68 1,752,999 4/1930 Phillips85/68 2,902,260 9/1959 Tilden 175/394 2,963,935 12/1960 Shields l 85/683,316,796 5/1967 Young 85/68 3,325,890 6/1967 Sandor 29/432 3,403,59310/1968 Moore 29/432 X 3,343,443 9/1967 Moore 29/432 UX' 3,372,7633/1968 Fischer 3,447,616 6/1969 Granat 175/394 FOREIGN PATENTS ORAPPLICATIONS 280,834 12/1964 Australia 85/68 85,165 5/1965 France 85/681,221,056 7/1966 Germany 85/68 Primary Examiner-Charlie T. MoonAttorney, Agent, or FirmMichael S. Striker [5 7] ABSTRACT The trailingend of a forwardly diverging first member is releasably engaged by thefront of a second member, the rear of which is configurated forengagement by a drill chuck. Both members are jointly rotated abouttheir common longitudinal axis to drill a hole into a wall with cuttingedges provided on the leading end of the first member. The second memberis then disengaged from the first member and withdrawn. An expansionmember having a slot in its front end is inserted into the hole and sooriented that the trailing end of the first member enters the slot,whereupon the expanding member is further driven into the hole so thatthe divergence of the first member radially expands the front end of theexpansion member as the trailing end enters deeper into the slot.

3 Claims, 9 Drawing Figures METHOD OFSET'IING AN EXPANSION ANCHORCROSS-REFERENCE TO RELATED APPLICATION This is a divisionof myco-pending application Ser. No. 23,339, filed on Mar. 27, 1970, now US.Pat. No. 3,715,952, under the title Expansion Anchor Unit.

BACKGROUND OF THE INVENTION The present invention relates generally toexpansion anchors, and more particularly to an expansion anchor unit.Specifically, the invention relates to the setting of an expansionanchor of such a unit.

Expansion anchors are of course not new per se. They are, in fact,available in a great variety of different types and sizes. One featurewhich most of the known expansion anchors have in common is that a holemust be drilled in a support structure before the expansion anchor canbe connected with the support structure. The drilling of such holesrequires a special drill which, when the hole is completed, is withdrawnto permit insertion of the expansion anchor. However, expansion anchorsmust be used in a great variety of different types of supportstructures, be they soft or hard, wood, plaster board, masonry or thelike. In order to accommodate all of these different possiblities thedrill used for making the hole is usually provided with cutting edges ofhard metal. If, as is sometimes the case, such a drill is usedoccasionally for do-it-yourself installation of an expansion anchor,then this arrangement is fully satisfactory. If, on the other hand, thedrill is used frequently for this purpose, as by a craftsman whoinstalls such expansion anchors as a part of his daily routine, thecutting edges will quickly become blunt. While it is true that they canbe sharpened again, this is possible only for a limited number of timesand very quickly thetime arrives when the drill must be replaced. This,evidently, is expensive, just as the repeated sharpening of the cuttingedges of a drill is time-consuming.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to avoid the aforementioned disadvantages.

More particularly it is an object of the present invention to provide animproved method of setting an expansion anchor, using an improvedexpansion anchor unit which is not possessed of these drawbacks.

In pursuance of the above objects, and others which will become apparenthereafter, one feature .of the present invention resides in a method ofsetting an expansion anchor in a support structure. It comprises thesteps of matingly but releasably engaging the trailing portion of afirst member, which diverges in direction towards its leading portionand is provided at the. same with cutting edges, with the forwardportion of an elongated second member whose rearward portion isconfigurated for engagement with a drilling tool; rotating both of themembers jointly about the longitudinal axis of the second member in asense causing drilling of a hole in a support structure by the cuttingedges; terminating drilling and withdrawing the second member from thehole; inserting into the hole an expansion member having a front portionprovided with at least one axially extendingslot, and orienting the slotso that the same is aligned with the trailing portion of the firstmember; and forcibly inserting the expansion member deeper into the holeso that the trailing portion of the first member enters into the slotand effects radial expansion of the front portion into wedgingengagement with the wall bounding the hole.

It is clear that the first member of the unit thus serves a dualpurpose, namely to drill its own hole and subsequently to act as theexpander member of the unit. This is a most simple and time-conservingas well as inexpensive method of mounting an expansion anchor unit in asupport structure, and it requires no tools other than those previouslyneeded, namely a power drill. Moreover, every time an expansion anchorunit is to be mounted in a support structure, a new set of cutting edgesis available, so that no loss of cutting efficiency due to blunting ofthe edges from the previous formation of an expansion anchor hole isexperienced. It is no longer necessary to sharpen blunted cutting edges,and the lost time and increased expense involved previously insharpening such cutting edges and eventually discarding the drillentirely have been eliminated according to the present invention.

Moreover, the material and the hardness of the first member providedwith the cutter edges can be selected in accordance with the fact thatthe cutter edges need withstand only a single drilling application,namely when the hole is drilled for the expansion anchor unit of whichthe first member having the cutting edges is a part. Thus, material canbe used which is considera bly less expensive than heretofore wasnecessary for making separate drills.

In addition, the first member is much more readily connectable with anddisconnectable from the second member, and vice versa, than thefrequently necessary removal and subsequent re-insertion of aconventional drill in the chuck of a power drilling machine.

The second member may itself serve exclusively the purpose of engagingthe first member while the latter is used to drill a hole in the supportstructure. Suscquently, the second member may be removed and a thirdmember, also constituting a part of a novel expansion anchor unitaccording to the present invention, may be inserted into the bore holein such a manner and to such an extent that it is expanded into tightengagement with the wall surrounding the hole by the first member whichat the completion of the drilling step has remained in the bore hole.The formation of the bore hole and the mounting of the expansion anchorunit therein is extremely simple when utilizing a unit according to thepresent invention, and it is fast as well as inexpensive. The thirdmember is essentially rod or bolt-shaped and optimum holding. conditionsin the bore hole are obtained if the diameter of the third membercorresponds to the diameter of the bore hole fonned by the first member.

The latter may be provided, incidentally, on its oppositelylongitudinally extending surfaces with one or more projecting ribs orprojections which are elongated substantially in longitudinal directionof the first member and engage in corresponding mating recesses providedon the second member or the third member, or on both. Such projectioncan be formed in simple manner by cold deformation when the first memberis produced, and they may converge gradually in the direction towardsthe leading portion and the cutter edges of the first member, which isto say that they diverge in the opposite direction and thus act as awedge which facilitates radial expansion of the expansion memberassociated with and forming a part of the noval unit. Their majorpurpose, however, is to provide proper engagement with either the secondmember or the third member, to prevent displacement of the first memberwith reference to either one of the others. Of course, these projectionsmay have other configurations, and

' may be located at different points of the first member as long asmating recesses are correspondingly provided on the second and/or thirdmember.

The second and/or third member may be provided with two or morehelically convoluted grooves in its outer circumferential surface, thepurpose being to allow escape of comminuted material of the supportstructure through these grooves to the outer side of the supportstructure. According to the invention the terminal portions of thesegrooves in the region of the forward end portion of the second and/orthird member which is engaged with the first member, will extend in atleast substantial axial parallelism with the axis of the second and/orthird member, and the projections of the first member will be lodged inthese terminal sections. So constructed, a particularly simple and easyconnection of the first member with the second and/or third member isachieved, and correspondingly an equally simple and easy disconnectionis obtainable. On the other hand, the projections abut against thelateral surfaces bounding the terminal sections of the grooves and thusrotation of the first with reference to the second and/or third membersis prevented during drilling. Such abutment further serves theadditional purpose of preventing deformation or breaking of theprojections during drilling.

It is advantageous if the first member is in form of a rather flatelongated member with the projections being located on the two oppositelateral surfaces of the same. Two or more such projections may beprovided, and if there are'two of them then they may be offset withreference to one another. The second and- /or third member may beprovided with a longitudinal slot, corresponding to the thickness of thefirst member-that is the dimension between the aforementioned twosurfaces of the sameand in which the first member is partiallyreceivable with its leading portion formed with the cutter edgesextending forwardly beyond the slot. The outer circumferential surfaceof the second member may be provided with recesses in diametrallyopposite edges bounding the slot and in these recesses the projectionsof the first member may be lodged when the first member is temporarilyconnected with the second member for drilling purposes. A first memberso configurated is particularly easy to manufacture, and the projectionsmay be formed simply by a stamping process as the first member is beingmanufactured. Similarly, the slot may be readily provided by milling orin other suitable manner in the second memher, and the recesses are thensubsequently formed also in suitable manner, for instance by milling.The opposite location of the projections, and the diametrally oppositelocation of the recesses, assures that lateral sliding of the firstmember out of the slot of the second member is prevented vented so thatthe first member will always be centered with reference to the secondmember, a consideration which is important during drilling.

The projections may be outwardly convexly curved, to facilitate and easethe expansion when the second member, or the third member, as the casemay be, is

driven into the bore hole to the extent necessary to provide suchexpansion. When such convex configuration is chosen, then there willonly be a line contact between the projections and the engaging surfaceportions of the second or third member, so that very little friction isopposed to the forcible insertion of the second or third member into thebore hole, making it possible for the second or third member to bereadily driven far into the bore hole with the first member entering farinto the slot of the second or third member and thereby obtaining anexcellent engagement of the expansion anchor unit in the expansionanchor hole, having a high resistance to forces tending to draw the unitout of the hole.

The projections may gradually merge out of the respective surfaces ofthe first member, so as to diverge in direction towards the cutter edgesthereof. However, it is possible to have the projections merge fromtheir widest or most divergent portion gradually tapering in thedirection towards both the leading and the trailing portion of the firstmember. This latter construction makes it possible to effect entry ofthe first member in either direction, a consideration which isparticularly of importance if the second member is not only anengagement for the first member during drilling with the latter, butalso constitutes the expansion member of the anchor unit. In this casethe first member will abut against an abutment portion in the slot ofthe expansion member so that the latter is not already expanded duringthe drilling period. Subsequently, the expansion member is withdrawnpartially or completely from the bore hole, at least to such an extentas to disconnect it from the first member, turned in circumferentialdirection until its longitudinal slot becomes aligned with the trailingportion of the first member, and then forcibly inserted into engagementwith the first member in a sense effecting the necessary expansion.

If the first member is of relatively flat configuration, and theprojections are located centrally on opposite surfaces thereof, thisaffords the possibility to form the second or third member with twoslots which cross one another so that at least the forward end portionof the second or third member is subdivided into four sections.Insertion of the second or third member into the bore hole in a sensecausing expansion by the first member then results in radial expansionof all four sections in four different directions, thus assuring astrong uniform expansion in all directions and a good anchoring of theunit. Moreover, the initial drilling characteristics afforded by a flatcutting edge are of course highly advantageous and can be provided bymaking the first member of flat configuartion.

Of course, the most simple form of the expansion anchor unit is for thesecond member to be not only the engaging member which engages with itsforward end portion the first member and with its rearward end portion adrilling tool, such as a power drill, but also to act subsequently todrilling as the expansion member itself which becomes expanded in andanchored in the bore hole in the support structure. This is not only themost inexpensive type of expansion anchor unit according to the presentinvention, but also requires the least amount of work for itsinstallation. lt goes without saying that with such a constructionstocking problems are also greatly reduced.

A very simple manner of making the second or third member of the novelexpansion anchor unit is to take a length of rod of polygonalcross-sectional configuration and to twist it about its longitudinalaxis, providing it at its forward end portion with engaging means forengaging the first member, and forming a longitudinal slot permittingsubsequent radial expansion. The slot may be increased stepwise forfacilitating such expansion. This method of construction provides in amost simple manner the helical grooves in the outer circumferentialsurface of the second member which are desirable for escape ofcomminuted material of the support structure. The stepwise increase ofthe longitudinal slot has the. additional advantage that the first stepmay serve as an abutment for the first member while the same is used todrill a bore hole in a support structure, so that premature expansion ofthe second member by the first member is avoided. At the same time thisguarantees that the leading portion of the first member provided withthe cutter edges will always project forwardly of the forward endportion of the second member, always assuming of course that the firststep of the slot is'located at such a spacing rearwardly from theforward end of the second member that this relation ship is obtained.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view showingone embodiment of a first member for an expansion anchor unit which canbe utilized for carrying out the method according to the presentinvention;

FIG. 2 is a view similar to FIG. 1 but illustrating a further embodimentof the first member;

FIG. 3 is a perspective view showing a second member for use with one ofthe members of FIGS. 1 and 2;

FIG. 4 is a perspective view showing a third member which, together withthe member of FIG. 3 and one of the members of FIGS. 1 and 2,constitutes an expansion anchor unit;

FIG. 5 is a view analogous to FIG. 4 but showing a member which bothserves to conect one of the members of FIGS. 1 and 2 with thenon-illustrated power drill, and which subsequently serves as theexpansion member of a two-member anchor unit;

FIG. 6 is a perspective view similar to FIG. 1 but illustrating yet anadditional embodiment of the first member;

FIG. 7 is an end view of a member similar to that of FIG. 6 but providedwith different projections;

FIG. 8 is a cross-sectional view illustrating, another embodiment of amember analogous to that of FIG. 6 but provided with differentprojectionsand inserted in an expansion member; and

FIG. 9 is a perspective view of a second or third member for anexpansion anchor unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing indetail and firstly the embodiment illustrated in FIG. 1, it will be seenthat what I have. shown in thisFigure is a first member for a two-partor three-part expansion anchor unit according to the present invention.The member 1 in FIG. 1 is the expander and drilling member of the unitand is provided with a trailing portion 2 serving subsequently forexpansion of the expansion member of the unit, and with a leadingportion 3 which is formed with conventional cutting edges 4. Thetrailing portion 2 is provided with a U-shaped cutout 5 extendingtowards but short of the leading portion 3 and being bounded at oppositesides by the arms or legs 6. These, it should be noted, conically orfrustoconically, taper in the direction away from the leading portion 3of the member 1. At opposite longitudinally extending surfaces 8 (onevisible) themember 1 is provided with respective substantially centrallylocated projections 9 which diverge outwardly of the respective surface8 in the direction towards the leading portion 3 and serve to furtherfacilitate expanding or spreading of an expansion member associated withthe member 1 as part of an expansion anchor unit according to thepresent invention. The bottom wall 7 of the cutout S constitutes anabutment.

The embodiment illustrated in FIG. 2 differs from that in FIG. 1 in thatthe member 10 which replaces the member 1 of FIG. 1, has its leadingportion 11corresponding to the portion 3 of the member 1 in FIG. 1madeof a thinner, flatter configuration than the portion 3 of the member 1.In other respects the member 10 corresponds to the member 1.

The member 12 identified and illustrated in FIG. 3 is not an expansionmember, but onlyconstitutes a connecting member connecting the member Iwith a power drill or the like used to rotate the member 1 so that thecutting edges 4 thereof will drill a hole in the nonillustrated supportstructure. A unit utilizing the member 12 must therefore have anadditional member which constitutes the expansion member of the unit andis identified with reference numeral 20 in FIG. 4, which will bediscussed presently. The member 12 in FIG. 3 is provided in its outercircumferential surface with at least two helically convoluted grooves13 through which comminuted material of the support structure can escapefrom the bore hole, thus facilitating the drilling operation. At itsforward end portion 14 the member 12 is provided with a centrallylocated impression 15 whose length and width--but not depth--correspondsto the respectively corresponding dimensions of the member 1 of FIG. 1or the member 10 of FIG. 2. The depth of the depression 15 is such thatwhen the member 1 or the member 10 is partially received therein, thebottom face 7 bounding the respective cut-out 5 will abut against thebottom face 16 bounding the depression 15, with the respective leadingportion 3 or 11 and the cutting edges provided thereon, extendingforwardly from the forward end portion 14. According to the presentinvention the terminal sections of the grooves 13 extend in at leastsubstantially parallelism withthe longitudinal axis of the member 12, asshown in FIG. 3, and the arms or legs 6 of the members l or 10 arereceived in these terminal sections at diametrically opposite sides ofthe member 12 when the members 1 or 10 are connected with the member 12,with the arms or legs 6 abutting against the side faces 17 bounding thegrooves, or rather the terminal sections of the grooves 13, to preventrelative rotation between the members 12 and l or 10 respectively. The

side faces 18 bounding the recess 15 serve the same purpose. Therearward portion 19 of the member 12 is configurated so it can beengaged readily by a tool, such as a power drill, which is used torotate the members 12 and I or in unison, so that the members 1 or 10will form their own bore holes in a support structure.

As mentioned before, an expansion anchor unit according to the presentinvention which utilizes either the member 1 or the member 10 of FIGS. 1and 2 in conjunction with the member 12 of FIG. 3 also requires anexpansion member which is identified with reference numeral 20 in FIG.4. It will be seen that it is provided with a conically tapering kerf 22in its leading end face 21, with this kerf merging into an axiallyextending slot 23 which extends through the member 20 almost half waytowards the trailing end face 26 thereof. The slot 23 subdivides theforward portion of the member 20 into two sections 24 which are spreadapart in radial direction when the member 20 is inserted into aboresubsequent to withdrawal of the member l2and forcibly driven intothe bore hole until the trailing portion 2 of the member 1 (or thetrailing portion 2 of the member 11) first enters the kerf 22 andsubsequently the slots 23, thus effecting radial spreading of thesections 24. A plurality of sawtooth profiled circumferential ridges 25is provided at least on the forward portion of the member 20, to affordtighter engagement of the sections 24 with the material of the supportstructure surrounding the bore hole. The trailing portion of the member20 is provided with an outer screw thread 27 which extends oversubstantially one-third of the length of the member 20, the intentionbeing that the portion provided with the screw thread 27 will extendoutwardly from the bore hole after the sections 24 have been expanded tothe maximum extent, so that an article to be secured to a supportstructure by means of the expansion anchor unit can be mounted on thisoutwardly extending portion, with a nut or the like being used to meshwith the screw threads 27 and secure such article in place. It goeswithout saying, of course, that the rear portion of the member 20 couldalso be hollow and the screw threads provided internally.

Coming to the embodiment in FIG. 5 it will be seen that the member 28illustrated therein replaces the members 12 and 20 of FIGS. 3 and 4. Themember 28 thus can be used with the members I or 10, respectively, andconstitutes with either one of the two a twomember expansion anchorunit, rather than the threemember expansion anchor unit previouslydescribed. The member 28 is provided not only with the slot 23-and alsowith the projections 25 corresponding to those of the member 20 in FIG.4but with an additional depression or recess corresponding to the oneidentified with reference numeral in FIG. 3, and extending in a planetransverse to the plane of the slot 23. This recess or depression isidentified with reference numeral 29. Extending rearwardly from therecess or depression 29 in axial direction of the member 28 and locatedat diametrally opposite sides of the member 28 are grooves 30 providedin the outer circumferential surface of the member 28. Thus, the members1 or 10 can be connected with the member 28 in the same manner as theycan be connected with the member 12 in FIG. 3, and their arms or legs 6will become lodged in the grooves 30. The latter, incidentally, can beformed by milling or in other suitable manner.

FIG. 6 shows that the member 1acorresponding to the members 1 and 10 ofFIGS. 1 and 2, respectively-- can be provided on its trailing portion 2awith elongated ridges 9a which extend substantially lengthwise of themember 1a, diverging outwardly from the respective surfaces in thedirection towards the leading portion 3 of the member la. They each have(one pro- 10 jection 9a is shown) a longitudinally extending abutmentedge 40.

FIG. 7 shows an embodiment which corresponds essentially to that of FIG.6, except that the projections of FIG. 6 are replaced by projections 9a,differing from the projections 90 only in that they are convexly curvedin direction outwardly away from the respective surfaces on which theyare provided.

The embodiment of FIG. 8 shows, in section and inserted in a member 19awhich is illustrated in FIG. 9, a further possible embodiment of themember 1a shown in FIG. 6. It is modified insofar as in FIG. 8 themember 1acorresponding to the member 1a of FIG. 6is provided withlongitudinally extending projections 9b which are produced bydeformation pressure, whereas those of the embodiment in FIG. 7 may forinstance be produced by cold forming of the material.

The member 19a shown in perspective in FIG. 9 in fragmentary form andshown in section in FIG. 8 is provided with a longitudinal slot 23corresponding to the similar slots in the preceding Figures. The membershown in FIG. 7, or the member 1a shown in FIG. 8, can be inserted intothis slot 23 for drilling purposes, and the projections 9a or 9b ofFIGS. 7 and 8 will become lodged in the grooves 41 which are formed, asclearly shown, in the outer circumferential surface of the member 19aalong diametrally opposite lateral edges of the slot 23. The projections9a or 9b abut against the surfaces 42 bonding one side of the grooves41, as evident for instance from FIG. 8. Of course, the projections 9aor 9b diverge in the same sense and direction as the projections 90 inFIG. 6. Thus, and because of their outwardly convex configuration, thereis only line contact between them and the surfaces bounding a slot in anexpansion member of the anchor unit, and this facilitates forcibleinsertion of the expansion member into the bore hole.

It will be appreciated that member 19a correspondsas illustrated-4o themember 12 of FIG. 3, that is an expansion anchor unit utilizing themember 19a and for instance the member 1a of FIG. 8, will additionallyhave a third member corresponding for instance to the member 20 of FIG.4. However, it would also be possible to modify the member 19a in such amanner that it could be used in the same manner as the member 28 of FIG.5, thus combining the functions of the members 12 and 20 of FIGS. 3 and4, respectively.

Of course, various different materials including, but not limited to,metallic material, are suitable for the various members of the expansionanchor units illustrated herein.

As indicated, the invention relates to a highly advantageous method ofmounting an expansion anchor in a support structure. Specifically, themember 12 is releasably engaged with one of the members 1 or 10, or themember 19a is releasably engaged with for instance the member shown inFIG. 7 or the member la shown in FIG. 8, and the members 18 or 19a arethen in turn engaged with the chuck of a power drill or the like, androtated so that the cutting edges 4 of the members 1, 10, la or the likewill form a bore hole in a support structure against which the cuttingedges 4 are placed. Thereupon, the member 12 or 19a is withdrawn fromthe bore hole, leaving the associated member (for instance the member I)behind in the bore hole. Now, an expansion member, such as the member 20of FIG. 4, is inserted into the bore hole and forcibly driven into thesame until the trailing portion-for instance the trailing portion 2 ofthe member l-enters into the slot 23 and expands the sections 24 intotight engagement with the material surrounding the bore hole. Of course,other expansion anchor units according to the present invention may beutilized in different manner, for instance the unit which has one of itstwo constituent components the member 28 of FIG. 5.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in anexpansion anchor unit, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoingwill so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the specific or generic aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

1. A method of setting an expansion anchor in a sup port structure,comprising the steps of matingly but releasably engaging the trailingportion of a first member which diverges in direction towards itsleading portion and is provided at the same with cutting edges, with theforward portion of an elongated second member whose rearward portion isconfigurated for engagement with a drilling tool; rotating both of saidmembers jointly about the longitudinal axis of said second member in asense causing drilling of a hole in a support structure by said cuttingedges; terminating drilling and withdrawing only said second member fromsaid hole; inserting into saidhole an expansion member having a frontportion provided with at least one axially extending slot, and orientingsaid slot so that the same is aligned with said trailing portion of saidfirst member; and forcibly inserting said expansion member deeper intosaid hole so that said trailing portion of said first member enters intosaid slot and effects radial expansion of said front portion intowedging engagement with the wall bounding said hole.

2. A method as defined in claim 1, wherein the step of rotatingcomprises engaging said rearward portion of said second member with arotary drilling tool, and rotating said first and second members byoperation of impacting a rear portion of said expansion member.

1. A method of setting an expansion anchor in a support structure,comprising the steps of matingly but releasably engaging the trailingportion of a first member which diverges in direction towards itsleading portion and is provided at the same with cutting edges, with theforward portion of an elongated second member whose rearward portion isconfigurated for engagement with a drilling tool; rotating both of saidmembers jointly about the longitudinal axis of said second member in asense causing drilling of a hole in a support structure by said cuttingedges; terminating drilling and withdrawing only said second member fromsaid hole; inserting into said hole an expansion member having A frontportion provided with at least one axially extending slot, and orientingsaid slot so that the same is aligned with said trailing portion of saidfirst member; and forcibly inserting said expansion member deeper intosaid hole so that said trailing portion of said first member enters intosaid slot and effects radial expansion of said front portion intowedging engagement with the wall bounding said hole.
 2. A method asdefined in claim 1, wherein the step of rotating comprises engaging saidrearward portion of said second member with a rotary drilling tool, androtating said first and second members by operation of said tool.
 3. Amethod as defined in claim 1, wherein the step of forcibly insertingsaid expansion member comprises impacting a rear portion of saidexpansion member.